Flares are common in patients with rheumatoid arthritis (RA), but many experience discordant inflammation and pain flares, according to study results published in BMC Rheumatology.

The study included patients from the Early RA Network (ERAN) cohort (n=719). The researchers assessed patients annually up to 11 years after presentation (3703 person-years of follow-up). The researchers defined flare events in 2 different ways, which were analyzed in parallel: Disease Activity Score-28 (DAS28) or pain flares. DAS28 flares satisfied Outcome Measures in Rheumatology (OMERACT) flare criteria: increases in DAS28 since the previous assessment (≥1.2 points if active RA or ≥0.6 points if inactive RA). Pain flares were defined as a ≥4.8-point worsening of Short Form Health Survey 36-Bodily Pain score.

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The researchers analyzed the first documented episode of each DAS28 and pain flare for each patient. They then used latent class analysis to determine subgroups with DAS28 and pain flares and compared clinical courses between subgroups.

After analyzing the results, the researchers found that 45% of patients experienced DAS28 flares and 52% experienced pain flares. Flares were usually discordant, with 60% of patients with DAS28 flare not concurrently in pain flare and 64% of patients with pain flare not concurrently in DAS28 flare.

The researchers identified 3 distinct DAS28 subgroups: the first characterized by increases in tender/swollen joint count (14.4%); the second by increases in symptoms (13.1%); and the third, which displayed lower flare severity (72.5%). They also identified 2 discrete pain flare subgroups: in the first the pain flare occurred following low disease activity and symptoms (88.6%) and in the second occurred on the background of ongoing active disease and pain (11.4%).

While DAS28 and pain flares had observed differences, both were associated with increased disability, which persisted after the flare.

The study included several limitations. The researchers noted that assessments may not have captured data during a flare’s peak, while pre-flare data may not reflect the patients best clinical status. In addition, missing data may have influenced the study findings.

“DAS28 and pain flares are discrete entities indicative of differing underlying mechanisms, but both have immediate patient impact and lead to longer term disability. Identifying and understanding RA flare subgroups should guide treatment,” the researchers wrote.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

McWilliams DF, Rahman S, James RJE, et al. Disease activity flares and pain flares in an early rheumatoid arthritis inception cohort; characteristics, antecedents and sequelae. [published online November 18, 2019]. BMC Rheumatol. doi:10.1186/s41927-019-0100-9